Force Sensing of Inputs Through Strain Analysis

ABSTRACT

An electronic device has a force sensor that determines a measure of applied force from a user contacting a cover glass of the device. In one embodiment, a frame at least partially encloses an interior of the electronic device and has an open end. A cover glass covers the open end of the frame and is movably connected to the frame to allow movement of the cover glass in response to one or more forces applied to an external surface of the cover glass. A plurality of strain probes is positioned under the cover glass, between the cover glass and the frame, and is arranged to output a plurality of strain signals response to the one or more forces applied to the cover glass. A force processing module is configured to at least calculate an amount of force applied to the cover glass based on the plurality of strain signals.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/776,592, filed Sep. 14, 2015, entitled “Force Sensing of InputsThrough Strain Analysis,” which is a 35 U.S.C. § 371 application ofPCT/US2013/032399, filed Mar. 15, 2013, entitled “Force Sensing ofInputs Through Strain Analysis,” the contents of which are incorporatedherein by reference as if fully disclosed herein.

TECHNICAL FIELD

This application generally relates to the use of force as an input to acomputing device, and more particularly to sensing force in a computingdevice and correlating the force to an input command to execute aproperty or command of the device.

BACKGROUND

Touch devices generally provide for identification of positions wherethe user touches the device, including movement, gestures, and othereffects of position detection. For a first example, touch devices canprovide information to a computing system regarding user interactionwith a graphical user interface (GUI), such as pointing to elements,reorienting or repositioning those elements, editing or typing, andother GUI features. For a second example, touch devices can provideinformation to a computing system suitable for a user to interact withan application program, such as relating to input or manipulation ofanimation, photographs, pictures, slide presentations, sound, text,other audiovisual elements, and otherwise.

It sometimes occurs that, when interfacing with a GUI, or with anapplication program, it would be advantageous for the user to be able toindicate an amount of force applied when manipulating, moving, pointingto, touching, or otherwise interacting with, a touch device. Forexample, it might be advantageous for the user to be able to manipulatea screen element or other object in a first way with a relativelylighter touch, or in a second way with a relatively more forceful orsharper touch. In one such case, it might be advantageous if the usercould move a screen element or other object with a relatively lightertouch, while the user could alternatively invoke or select that samescreen element or other object with a relatively more forceful orsharper touch.

Each of these examples, as well as other possible considerations, cancause one or more difficulties for the touch device, at least in thatinability to determine an amount of force applied by the user whencontacting the touch device might cause a GUI or an application programto be unable to provide functions that would be advantageous. When suchfunctions are called for, inability to provide those functions maysubject the touch device to lesser capabilities, to the possibledetriment of the effectiveness and value of the touch device. On theother hand, having the ability to provide those functions might providethe touch device with greater capabilities, to the possible advantage ofthe effectiveness and value of the touch device.

SUMMARY

Examples of embodiments described herein may take the form of anelectronic device, comprising a frame at least partially enclosing aninterior of the electronic device, the frame having an open end; a coverglass covering the open end of the frame, the cover glass movablyconnected to the frame to allow movement of the cover glass in responseto one or more forces applied to an external surface of the cover glass;a plurality of strain probes arranged to output a plurality of strainsignals responsive to the force applied to the cover glass; and a forceprocessing module configured to at least calculate an amount of forceapplied to the cover glass based on the plurality of stain signals.

Some embodiments further comprise an array of sensing elements arrangedto output a plurality of sense signals that indicate a location on thecover glass of one or more touches; wherein the force processing moduleis further configured to calculate a force applied to the cover glass ateach touch location based on the strain signals and the sense signals.

In some embodiments, the force processing module calculates the forceapplied at two or more touch locations by first calculating a centroidof a total force applied and then calculating the force applied at eachtouch location based on the centroid of the total force and the locationof each touch as indicated by the sense signals.

Some embodiments further comprise a cover glass support member fixedlyconnected to the frame and in supportive contact with the cover, theplurality of strain probes being associated with the support member.

In some embodiments, the cover glass support member comprises an uppersupport comprising an upper surface in supportive contact with the coverglass; a lower support fixedly connected to the frame; and a bendingbeam disposed between the upper and lower support, the plurality ofstrain probes disposed on the bending beam; wherein the movement of thecover glass causes the upper support to move towards the lower supportthereby deforming the bending beam, the deformation of the bending beamcausing a corresponding change in the output from the strain probes.

In some embodiments, the upper support includes a plurality of pedestalsdisposed on a lower surface of the upper support, the plurality ofpedestals concentrating the force imparted from the cover glass ontodiscrete areas along the bending beam.

In some embodiments, the cover glass support member further comprises aplurality of flexures, each flexure comprising an upper strain probedisposed on the upper surface of the bending beam; and a lower strainprobe disposed on the lower surface the bending beam.

In some embodiments, each pedestal has a first flexure adjacent to afirst side of the pedestal and a second flexure adjacent to a secondside of the pedestal.

In some embodiments, each pedestal is associated with a wheatstonebridge that interconnects the upper and lower strain probes of the firstflexure and the upper and lower strain probes of the second flexure.

In some embodiments, the lower support includes a stop surface thatprevents further movement of the cover glass when the lower surface ofthe bending beam contacts the stop surface.

In some embodiments, the cover glass support member comprises at leastone bending beam that is in supportive contact with the cover glass; aplurality of clips, wherein each clip attaches a bending beam end to aninterior of the frame, each clip having one of the plurality of strainprobes disposed thereon; wherein the movement of the cover glass causeseach of the clips to rotate, thereby causing a corresponding change inthe output from the strain probes.

In some embodiments, the cover glass further comprises an opaque regionlocated along a perimeter of the cover glass; wherein the plurality ofstrain probes are located on an interior surface of the cover glasswithin the opaque region.

Some embodiments further comprise a compressible layer connected on afirst side to the interior surface of the cover glass within the opaqueregion and connected on a second side fixed datum within the interior ofthe electronic device.

Some embodiments further comprise an elastomeric border connected to theframe and disposed between the cover glass and the frame; and acompressible layer connected on a first side to the interior surface ofthe cover glass within the opaque region and connected on a second sideto the elastomeric border.

Examples of embodiments described herein may take the form of a supportmember for a cover glass component of an electronic device, comprisingan upper support comprising an upper surface adapted to be in supportivecontact with the cover glass; a lower support adapted to be fixedlyconnected to a frame of the electronic device; and a bending beamdisposed between the upper and lower support; and a plurality of strainprobes disposed on the bending beam; wherein a movement of the coverglass causes the upper support to move towards the lower support therebydeforming the bending beam, the deformation of the bending beam causinga corresponding change in the output from the strain probes.

In some embodiments, the upper support includes a plurality of pedestalsdisposed on a lower surface of the upper support, the plurality ofpedestals concentrating a force imparted from the cover glass ontodiscrete areas along the bending beam.

Some embodiments further comprise a plurality of flexures, each flexurecomprising an upper strain probe disposed on the upper surface of thebending beam; and a lower strain probe disposed on the lower surface thebending beam.

In some embodiments, each pedestal has a first flexure adjacent to afirst side of the pedestal and a second flexure adjacent to a secondside of the pedestal.

In some embodiments, each pedestal is associated with a wheatstonebridge that interconnects the upper and lower strain probes of the firstflexure and the upper and lower strain probes of the second flexure.

In some embodiments, the lower support includes a stop surface thatprevents further movement of the cover glass when the lower surface ofthe bending beam contacts the stop surface.

Examples of embodiments described herein may take the form of a supportmember for a cover glass component of an electronic device, comprisingat least one bending beam adapted to be in supportive contact with thecover glass; a plurality of clips, wherein each clip is adapted toattach a bending beam end to an interior of the frame, each clip havingone of the plurality of strain probes disposed thereon; wherein amovement of the cover glass causes each of the clips to rotate, therebycausing a corresponding change in the output from the strain probes.

Examples of embodiments described herein may take the form of a coverglass component of an electronic device, comprising an opaque regionlocated along a perimeter of the cover glass; a plurality of strainprobes located on an interior surface of the cover glass within theopaque region.

Some embodiments further comprise a compressible layer connected on afirst side to the interior surface of the cover glass within the opaqueregion and connected on a second side fixed datum within the interior ofthe electronic device.

Some embodiments further comprise an elastomeric border connected to theframe and disposed between the cover glass and the frame; and acompressible layer connected on a first side to the interior surface ofthe cover glass within the opaque region and connected on a second sideto the elastomeric border.

While multiple embodiments are disclosed, including variations thereof,still other embodiments of the present disclosure will become apparentto those skilled in the art from the following detailed description,which shows and describes illustrative embodiments of the disclosure. Aswill be realized, the disclosure is capable of modifications in variousaspects, all without departing from the spirit and scope of the presentdisclosure. Accordingly, the drawings and detailed description are to beregarded as illustrative in nature and not restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming the subject matter that is regarded as formingthe present disclosure, it is believed that the disclosure will bebetter understood from the following description taken in conjunctionwith the accompanying Figures, in which:

FIG. 1 is a perspective illustration of an electronic device embodimentthat includes a force sensor;

FIG. 2A is a top plan view of another electronic device embodiment thatincludes a force sensor;

FIG. 2B is a top plan view of still another electronic device embodimentthat includes a force sensor;

FIG. 3 is a schematic illustration of a cover glass in accordance withembodiments discussed herein;

FIG. 4 is a cut-away illustration of the cover glass embodiment shown inFIG. 3;

FIG. 5 is perspective illustration of an embodiment of the beam andcover glass construct shown in FIG. 4;

FIG. 6 is perspective illustration of an alternative embodiment of thebeam and cover glass construct shown in FIG. 4;

FIG. 7 is an enlarged cross-sectional view of a flexure shown in FIG. 5;

FIG. 8 is schematic illustration of a beam having a number of strainprobes incorporated into the bending beam portion of the beam;

FIG. 9 is circuit diagram showing the interconnections among the strainprobes shown in FIG. 8;

FIG. 10 is a perspective illustration of frame for the cover glass shownin FIG. 3;

FIG. 11A is a schematic illustration of cover glass embodiment having amoveable attachment to a device datum or other fixed position within atouch I/O device;

FIG. 11B is a schematic illustration of cover glass embodiment having amoveable attachment to an elastomeric member that provides a seat orother border between the frame and the cover glass of a touch I/Odevice;

FIGS. 12A-12D illustrate an alternative embodiment of a cover glass andcover glass support in accordance with embodiments discussed herein;

FIG. 13 is a schematic illustration of a user applying a single force toa cover glass by pressing downward with one finger; and

FIG. 14 is a schematic illustration of a user applying multiple forcesto a cover glass by pressing downward with more than one finger;

FIG. 15 is a flow chart that illustrates a method embodiment directed todetermining an amount of force applied to an electronic device through ainput surface;

FIG. 16 is a flow chart that illustrates a method embodiment directedperforming the processing operation of FIG. 15;

FIG. 17 is a top plan view of the electronic device of FIG. 2A thatshows a number of forceful touches to the input surface;

FIG. 18 is chart showing force amounts measured at the individualflexures shown in FIG. 10 for a number of the forceful touches of FIG.17;

FIG. 19 is a flow chart showing a method embodiment directed todetermining a location of single force applied to an input surface;

FIG. 20 is a flow chart showing a method embodiment directed todetermining the locations of multiple forces applied to an inputsurface;

FIG. 21 shows a conceptual drawing of communication between a touch I/Odevice and a computing system; and

FIG. 22 shows a conceptual drawing of a system including a touch sensingand force sensing I/O device.

DETAILED DESCRIPTION

The present disclosure is related to a force sensing device that may beincorporated into a variety of electronic or computing devices, such as,but not limited to, computers, smart phones, tablet computers, trackpads, and so on. The force sensing device may be used to detect one ormore user force inputs on an input surface and then a processor (orprocessing element) may correlate the sensed inputs into a forcemeasurement and provide those inputs to the computing device. In someembodiments, the force sensing device may be used to determine forceinputs to a track pad, a display screen, or other input surface.

The force sensing device may include an input surface that provides anengagement surface for a user, such as the external surface of a trackpad or the cover glass for a display. In other words, the input surfacemay receive one or more user inputs directly or indirectly. The forcesensing device includes a force sensor that may be implemented as astrain gauge or other circuit element that is response to forces appliedto the input surface. The force sensor is operatively coupled to theinput surface such that the force sensor responds when a user pressesagainst the input surface with a finger, thumb, stylus, or other object.The input surface is moveably connected a body or frame of theelectronic device such that the input surface displaces a certain amountwhen pressed. Movement of the input surface stresses the force sensor orstructures associated with the force sensor such that the force sensoroutputs a strain signal that is responsive to the applied stress.

The force sensor sensing device may include a plurality of force sensorsthat are located at various points along the perimeter of the inputsurface. In one embodiment, the force sensing device includes a numberof bending beams that extend along the perimeter of input surface. Forcesensors located on the bending beam respond as the bending beam bends inresponse to forces applied to the input surface. In another embodiment,the force sensing device is movably connected to the input surfacethrough an elastomeric or otherwise compressible member located betweenthe input surface and a device datum or other fixed point within thedevice Force sensors connected to an interior of the input surfaceproximate to the edges of the input surface respond as the input surfacemoves. In still another embodiment, the force sensing device includes anumber of bending beams that attach to the body or frame of theelectronic device through a number of rotatable clips. Force sensorslocated on the rotatable clips respond as the bending beam moves theclips in response to forces applied to the input surface.

In some embodiments, the force sensing device may be incorporated intoor used in conjunction with a touch sensitive device. In theseembodiments, touch inputs detected by the touch device may be used tofurther refine the force input location, confirm the force inputlocation, and/or correlate the force input to an input location. In thelast example, the force sensitive device may not use the capacitivesensing of the force sensing device to estimate a location, which mayreduce the processing required for the force sensing device.Additionally, in some embodiments, a touch sensitive device may be usedto determine force inputs for a number of different touches. Forexample, the touch positions and force inputs may be used to estimatethe input force at each touch location.

The strain signals output from the sensors are received by theprocessor, which processes the strain signal to determine an amount offorce applied to the input surface. Here, the processor may calculatethe forces applied locally at a particular force sensor or group offorce sensors, and then sum the locally applied forces to determine atotal amount of applied force. The processor may also estimate orotherwise determine a centroid for the applied force on the inputsurface based on the proportion of the total force applied at each forcesensor or group of force sensors. In the event that the user applied theforce using one finger or other object, the force centroid may be takento be the location on the input surface where the force was applied. Ifthe electronic device is a touch sensitive device or otherwise includesa mechanism for separately determining the location of touch inputs,this mechanism may be used in combination with the force sensing deviceto determine the force applied at each touch location when the userapplies the force using more than one finger or other object. Here,force applied at a particular touch location is determined based on theproximity of the touch location to the force centroid.

Electronic Device Embodiments

Turning now to the figures, illustrative electronic devices that mayincorporate the force sensing device will be discussed in more detail.FIGS. 1, 2A, and 2B illustrate various computing or electronic devicesthat may incorporate the force sensing device. With reference to FIG. 1,the force sensing device may be incorporated into a computer 1000, suchas a laptop or desktop computer. The computer 1000 may include a trackpad 1200 or other input surface, a display 1400, and an enclosure 1600or frame. The enclosure 1600 may extend around a portion of the trackpad 1200 and/or display 1400. In the embodiment illustrated in FIG. 1,the force sensing device may be incorporated into the track pad 1200,the display 1400, or both the track pad 1200 and the display 1400. Inthese embodiments, the force sensing device may be configured to detectforce inputs to the track pad 1200 and/or the display 1400.

In some embodiments, the force sensing device may be incorporated into atablet computer. FIG. 2A is a top perspective view of a tablet computerincluding the force sensing device. With reference to FIG. 2A, the tablecomputer 1000 may include the display 1400 where the force sensingdevice is configured to detect force inputs to the display 1400. Inaddition to the force sensing device, the display 1400 may also includeone or more touch sensors, such as a multi-touch capacitive grid, or thelike. In these embodiments, the display 1400 may detect both forceinputs, as well as position or touch inputs.

In yet other embodiments, the force sensing device may be incorporatedinto a mobile computing device, such as a smart phone. FIG. 2B is aperspective view of a smart phone including the force sensing device.With reference to FIG. 2B, the smart phone 1000 may include a display1400 and a frame or enclosure 1600 substantially surrounding a perimeterof the display 1400. In the embodiment illustrated in FIG. 2B, the forcesensing device may be incorporated into the display 1400. Similarly tothe embodiment illustrated in FIG. 2A, in instances where the forcesensing device may be incorporated into the display 1400, the display1400 may also include one or more position or touch sensing devices inaddition to the force sensing device.

Force Sensor Embodiments

Turning now to example force sensors, reference is made to FIG. 3 whichis a schematic illustration of a cover glass 3000 for the electronicdevice shown in FIG. 2A. The following force sensor discussionreferences the electronic device shown in FIG. 2A by way of example andnot limitation. The various force sensors discussed herein may beincorporated in other electronic devices depending upon the application.The cover glass 3000 has an interior facing surface 3004 and an exteriorfacing surface 3008. The cover glass 3000 shown in FIG. 3 is orientedsuch that the interior facing surface 3004 is shown in the figure. Whenincorporated in an electronic device 1000, the cover glass 3000 isconnected to a frame or other enclosure such that the frame and coverglass 3000 enclose an interior space of the electronic device 1000. Auser may enter inputs into the electronic device through forcefultouches on the exterior surface 3008 of the cover glass 3000. Circuitsadapted to be responsive to the forceful touch input are disposedproximate to the underside or interior facing surface 3004 of the coverglass 3000.

As shown in FIG. 3, the cover glass 3000 may include a number of beams3012 disposed along a perimeter 3016 of the cover glass 3000. The beams3012 are attached to the interior facing surface 3004 of the cover glass3000. In accordance with embodiments discussed herein, the beams 3012function to both support the weight of the cover glass 3000 and toprovide a mounting or other location for a number of strain probes thatare configured to measure a force applied to the exterior surface 3008of the cover glass 3000.

The construction of a beam 3012 in accordance with embodiments discussedherein may be seen in more detail in FIG. 4. FIG. 4 is a cut-awayillustration of the cover glass 3000 embodiment shown in FIG. 3. In FIG.4, the exterior facing surface 3008 of the cover glass 3000 is facingupward, and the interior facing surface 3004 of a cover glass 3000 isfacing downward. As can be seen in FIG. 4, the beam 3012 includes anupper support 4004 that is attached to the interior facing surface 3004of the cover glass 3000. The beam 3012 additionally includes a lowersupport 4016 that is attached to the frame of the electronic device1000. The beam 3012 additionally includes a bending beam 4008 disposedbetween the upper support 4004 and the lower support 4016. The beam 3012includes a number of interior spaces which allow the upper support 4004to move towards the interior of the electronic device 1000 when a forceis applied to the exterior surface 3008 of the cover glass 3000. Saidanother way, when a user applies a force by, for example, pressing witha finger on the exterior surface 3008 of the cover glass 3000, the beam3012 compresses such that the upper support 4004 moves towards the lowersupport 4016. Because the lower support 4016 is rigidly or fixedlyattached to the frame of the electronic device 1000, the cover glass3000 moves with respect to the frame when the force is applied.

FIG. 5 and FIG. 6 are cross sectional illustrations of the beam andcover glass construct shown in FIG. 4. The location of the cross sectionof FIG. 5 and FIG. 6 is indicated in FIG. 3 as cross section 5. Turningfirst to FIG. 5, the cross sectional view of this figure shows the coverglass 3000 attached to the beam 3012 at the interior surface 3004 of thecover glass 3000. As can be seen in FIG. 5, a layer of adhesive 5004 maybe used to attach the cover glass 3000 to the beam 3012. As can befurther seen in FIG. 5, the beam 3012 includes an upper support 4004, abending beam 4008, and a lower support 4016. As can be seen in FIG. 5,the upper support 4004 may include a number of pedestals 5008, or suchpedestals may be separately formed and adjacent or attached to the uppersupport. Each pedestal 5008 is typically disposed on the interior facingsurface 5012 of the upper support 4004. The pedestal 5008 extendsdownwardly from the interior facing surface 5012 to contact an upwardfacing surface of the bending beam 4008. The pedestal 5008 functions toconcentrate the force or forces applied to the exterior surface 3008 ofthe cover glass 3000 onto specific areas of the bending beam 4008. Thepedestal 5008 additionally forms interior spaces 5016 between the uppersupport 4004 and the bending beam 4008. As can be seen in FIG. 5, theinterior spaces 5016 are located between the lower surface 5012 of theupper support 4004 and the upper surface 5020 of the bending beam 4008.

Due to the presence of the pedestals 5008, the bending beam 4008 willflex downward in response to an applied force at the locations of thepedestals 5008. In this regard, the lower support 4016 may include anumber of interior spaces 5024 which allow the bending beam 4008 to flexin response to an applied force. As can be seen in FIG. 5, the lowersupport 4016 contains a number of interior spaces 5024 disposed betweena lower or interior surface 5028 of the bending beam 4008 and an uppersurface 5032 of the lower support 4016. Because the lower support 4016is rigidly connected to the frame, the surface 5032 provides a stoppingsurface for the bending beam 4008. It should be appreciated that theorientation of the stopping surface 5032 shown in FIG. 5 is by a way ofexample and not limitation. In accordance with alternative embodimentsthe stopping surface 5032 may be a raised or otherwise removed from theexterior or upwardly facing surface to provide an upwardly facingpedestal which engages the bending beam 4008 when a force is applied tothe cover glass 3000.

The width of the pedestals 5008 shown in FIG. 5 is by way of example andnot limitation. The pedestals 5008 shown in FIG. 5 are relatively wide.In accordance with alternative embodiments, the upper support 4004 mayinclude relatively narrow pedestals 6008, such as in the alternativeconstruction illustrated in FIG. 6. The narrow pedestal 6008 shown inFIG. 6 may function similarly to the wide pedestal shown in FIG. 5.Specifically, the pedestal 6008 may function to concentrate forceapplied to the exterior surface of the cover glass 3000 to specificpoints along the bending beam 4008.

As can be seen in FIGS. 5 and 6, the bending beam 3012 includes a numberof flexures 5036. Each flexure is adjacent to at least one pedestal 5008and may be disposed between two pedestals 5008. Each pedestal 5008 isthus typically disposed between two flexures 5036, one on each side ofthe pedestal 5008. The flexure 5036 includes at least one strain probe5040, which is adapted to measure a strain as the bending beam 4008flexes with an applied force. As can be seen in FIGS. 5 and 6, theflexure 5036 includes portions of the interior spaces 5016 and 5024. Inthis regard, the flexure 5036 is provided with room through which theflexure 5036 may move to register an amount of bending in the bendingbeam 4008 that occurs in response to an applied force.

FIG. 7 is an enlarged cross-sectional view of a portion of an individualflexure 5036, which may be suitable for use in the structure shown inFIG. 5 or FIG. 6. As can be seen in FIG. 7, the flexure portion isadjacent to the pedestal 5008. The flexure portion includes interiorspaces 5016 and 5024 which allow for bending of the bending beam 4008 atthe flexure 5036. In accordance with the embodiments discussed herein,the flexure 5036 provides a mounting area for one or more strain probes.As can be seen in FIGS. 5 and 6, the strain probes may be disposed onthe upward facing surface of the bending beam 4008. However, thisconfiguration is by way of example and not limitation. In accordancewith other embodiments the strain probes are incorporated into theinterior of the bending beam 4008. Such an embodiment is illustratedschematically in FIG. 8.

FIG. 8 is a schematic illustration of an individual flexure 5036, whichmay be suitable for use in the structure shown in FIG. 5 or FIG. 6. Ascan be seen in FIG. 8, the bending beam 4008 may include four strainprobes 8004 a-d. In this arrangement two strain probes 8004 a, b arelocated approximate to the upper surface of the bending beam 4008.Similarly, the bending beam 4008 includes two strain probes 8004 c, ddisposed proximate to the lower surface of the bending beam 4008. Inaccordance with embodiments discussed herein, the strain probes 8004 a-dmay be arranged in a Wheatstone bridge configuration shown in FIG. 9. Itshould be appreciated that the arrangement of strain gauges and circuitshown in the figures is by way of example and not limitation. Certainembodiment within the scope of this disclosure may have greater or fewerstrain gauges and differing circuits for receiving strain gauge output,depending on the application.

As discussed above, the beam 3012 may be attached to a frame whichencloses an interior of the electronic device 1000. Such a frame isillustrated in FIG. 10 and generally is identified with referencenumeral 10004. FIG. 10 additionally includes the location for a numberof pedestals 5008 and flexures 5036 a 1-h 2 in accordance with anembodiment discussed herein. As shown in FIG. 10, this arrangementorganizes the exterior surface of the electronic device 1000 into eightregions, each region containing one pedestal and two flexures. The leftside of the electronic device 1000 includes four regions L1-L4. RegionsL1 and L4 are smaller and located proximate to the corners of theelectronic device 1000. Similarly the right side of the electronicdevice 1000 includes four sections R1-R4, with sections R1 and R4 beingsmaller and located near the corners of the device.

The orientation of pedestals 5008, flexures 5036 a 1-h 2 and theassociated sections shown in FIG. 10 is by way of example and notlimitation. In other embodiments, the strain gauges and/or pedestals5008 may be located at the corners of the device. In still otherembodiments, the strain gauges and/or pedestals 5008 are located beneaththe display stack instead of or in addition to being located around theperimeter of the device. The arrangement of strain gauges and/orpedestals 5008 need not be symmetrical or have the same number of gaugeson opposing sides. In addition, the corners of the cover glass 3000 orthe beam 3012 supporting the cover glass 3000 may be attached to theframe 10004 at the corners of the device. This attachment may be throughbolting the beam to frame 10004, making the beam 3012 part of the frame10004 or attaching the beam 100004 or the cover glass 3000 itself to theframe 100004 with VHB or similar adhesive. The cover glass 3000 near anddirectly above these attachment points may be relatively insensitive toapplied force; however, the use of bending flexures 5036 as described inFIG. 10 will allow force to be detected and measured at all other partsof the cover glass 3000.

FIGS. 11A and 11B illustrate another force sensor in accordance withembodiments discussed herein. FIG. 11A shows the cover glass 3000 havinga moveable attachment to a device datum or other fixed position 1308.The cover glass 3000 is attached to a compressible or elastomeric member13004 between the cover glass 3000 and the datum 13008. The cover glass3000 additionally includes a black mask area 13012. Generally, the blackmask area 13012 covers circuitry or other components contained withinthe interior of the electronic device and located near a border regionof the cover glass 3000. The black mask area 13012 provides a border fora transparent area 13024, which is adapted to receive touch input and todisplay a graphical user interface or other visible icons on the surfaceof the cover glass 3000. As can be seen in FIG. 11A, the embodimentadditionally includes a strain gauge 13016 disposed on the underside ofthe cover glass 3000 in the black mask area 13016.

The embodiment shown in FIG. 11A has a cover glass 3000 with an edgethat substantially corresponds to the edge of the electronic device1000. In accordance with alternative embodiments, the electronic device1000 may include a rubber or other elastomeric member 13020 whichprovides a seat or other border between the frame and the cover glass3000. This configuration is illustrated in FIG. 11B and the elastomericborder is generally identified with reference numeral 13020. As can beseen in FIG. 11B, the embodiment additionally includes a compressible orother elastomeric member 13004 between the cover glass 3000 and theborder member 13020. As can be seen in FIG. 11B, the embodimentadditionally includes a strain probe or strain gauge 13016 disposed onthe underside of the cover glass 3000 in the black mask area 13012. Asthe user applies a force to the exterior surface of the cover glass3000, the strain gauge 13016 located in the black mask area 13012 isthereby actuated. In some instances, it may be beneficial to sense thestrain difference between two points in the black mask 13012 so twostrain sensors 13016 may be placed so they detect the strain difference.Moreover, it may be beneficial to detect the strain both perpendicularand parallel to the boundary so it may be useful to use two strain gages13016, one oriented perpendicular to the boundary and one orientedparallel to the boundary.

FIG. 12A illustrates another strain based force sensing approach inaccordance with embodiments discussed herein. The following force sensordiscussion references the electronic device shown in FIG. 2B by way ofexample and not limitation. The force sensors shown in FIGS. 12A-12D maybe incorporated in other electronic devices depending upon theapplication. As can be seen in FIG. 12A, the embodiment may include aclip or a number of clips 14004 which are rigidly attached to the frame10004. As an example, a clip (14004) is shown in greater detail in FIG.12B. As seen in FIG. 12B, the clip 14004 includes a strain gauge 14012oriented in a vertical direction. The top surface of the clip 14004 isrigidly attached to the cover glass 3000, and the bottom surface of theclip is rigidly attached to the frame. When the user applies a force tothe cover glass 3000, the force exerts a downward pressure deforming theclip by causing a rotation around the pivot 14016 and generating strainon 14012, which would then be measured using the strain gage 14012.Another example of strain sensing following the approach in FIG. 12A isshown in FIG. 12D. In this example, a bending beam, which can be seen ingreater detail in FIG. 12D, is used to detect deflection. The beam isrigidly connected to the frame at two mounting holes on both ends asshown in FIG. 12D. The cover glass 3000 is pushing on the beam on thepost in the center of the beam. When the user applies a force to thecover glass 3000, this force exerts a downward pressure on the bendingbeam which, in turn, causes the clip 14004 to rotate about a fixed point14016. This rotation of the clip 14004 actuates the strain gauge 14012causing the strain gauge to measure a strain that occurs due to themovement of the cover glass 3000.

Force Sensing Methods

FIGS. 13 and 14 illustrate force inputs that may be measured inaccordance with embodiments discussed herein. In some instances, forcesensor embodiments may be used to measure the force applied by a singletouch. Specifically, as can be seen in FIG. 13, a user may apply asingle force to the cover glass 3000 by pressing downward with onefinger. Here, the strain probes arranged around the perimeter of thecover glass 3000 measure the force applied. In other instances, the usermay press downward with more than one finger. For example, as shown inFIG. 14, a first force 15008 and second force 15012 are applied to thecover glass 3000. In response to this multi-force touch input, thesystem may first determine a centroid 15016 for the combined force.Specifically, the strain probes arranged around the perimeter of thecover glass may calculate the centroid or the location and amount of thecentroid through measurements along the perimeter. Following this, thetouch I/O system may establish the points on the cover glass for theindividual touch inputs. Following this, the system may calculate theforce of each touch input based on the location of the touch input andbased on the location and amounts of the force input centroid 15016.Methods for measuring applied forces and the locations of applied forcesare discussed in greater detail below. Certain portions of the followingdiscussion reference the force sensor shown in FIG. 3 by way of exampleand not limitation. It should be appreciated that the methods discussedbelow can be generally applied to the various sensor mechanismsdiscussed herein.

FIG. 15 is a flow chart that illustrates a method embodiment directed todetermining an amount of force applied to an electronic device 1000through an input surface. Initially, in operation 15006, the electronicdevice 1000 senses strain through the operation of strain sensors thatare responsive to force applied to an input surface of the electronicdevice 1000. Operation 15010 occurs flowing operation 15006. Inoperation 15010, the strain sensors output strain signals, which arereceived as input to a processor, controller, or other computationalelement. Operation 15016 occurs flowing operation 15010. In operation15016, the processor processes the strain signals to determine an amountof force applied to the input surface of the electronic device 1000.

FIG. 16 is a flow chart that illustrates a method embodiment directed toperforming the processing operation of FIG. 15. Initially, in operation16004, the processor determines an equivalent strain for each flexure.For the flexure arraignment shown in FIG. 8 and having the Wheatstonebridge connection shown in FIG. 9, the equivalent strain may becalculated according to the following equation:

Equivalent Strain=0.5*(S1−S2−S3+S4)   (1)

Operation 16008 occurs flowing operation 16004. In operation 16008, theprocessor determines an amount of applied force at each flexure usingthe equivalent strains for each flexure. Here, the processor may apply ascaling factor that translates equivalent strain into applied force. Thescaling factor may be an empirically derived quantity that is found tomost closely convert the equivalent strain to the correct applied forcefor a number of locations on the input surface. For example, a scalingfactor of 2.4 μstrain/gm was derived using the data points illustratedin FIG. 17, which is a top plan view of the electronic device of FIG.2A. FIG. 17 shows a number of forceful touches, labeled as DP1, DP2,DP3, DP4, DP5 and DP6, to the input surface. Each touch occurred overthe area of the force circle near each label. The centroid derived fromthe raw strain gage data is shown as the small square inside each forcecircle. Each touch illustrated represents a 10 gf load. Applying the 2.4μstrain/gm scaling factor to strain data produced by the loads gave theapplied for data shown in FIG. 18, which is chart showing force amountsmeasured at the individual flexures shown in FIG. 10 for a number of theforceful touches of FIG. 17. The specific data points described aboveare merely examples and the particular scaling factor used in particularcase will vary depending on the application according to such conditionsare electronic device type, anticipated load amounts, cover glass ortouch pad construction, and so.

Operation 16012 occurs flowing operation 16008. In operation 16012, theprocessor determines the total force applied to the input surface usingthe forces applied at each flexure. More specifically, the processorsums the individual applied forces to arrive at total force amount thatis applied to the input surface.

FIG. 19 is a flow chart showing a method embodiment directed todetermining a location of single force applied to an input surface. Inoperation 19004, the processor calculates the proportion of the totalforce that was applied at each individual flexure. Operation 19008occurs flowing operation 19004. In operation 19008, the processordetermines the distances between each individual flexure and the pointof force application on the input surface using the proportion of thetotal force that was applied at each individual flexure. Operation 19012occurs flowing operation 19008. In operation 19012, the processordetermines the location of the point of force application on the inputsurface using that point's distance from each individual flexure.

FIG. 20 is a flow chart showing a method embodiment directed todetermining the locations of multiple forces applied to an inputsurface. In operation 20004, the processor calculates the proportion ofthe total force that was applied at each individual flexure. Operation20008 occurs flowing operation 20004. In operation 20008, the processordetermines the distances between each individual flexure and thecentroid of the applied force on the input surface using the proportionof the total force that was applied at each individual flexure.Operation 20012 occurs flowing operation 20008. In operation 20012, theprocessor determines the location of the applied force centroid on theinput surface using the centroid's distance from each individualflexure. Operation 200016 occurs flowing operation 20012. In operation20016, the processor determines the location of each individual touchusing sense data acquired when force was applied to the input surface.Operation 20020 occurs flowing operation 20016. In operation 20020, theprocessor determines the force applied at each individual touch locationusing the total applied force and the location of the force centroid.

Example System Architecture

FIG. 21 shows a conceptual drawing of communication between a touch I/Odevice and a computing system.

FIG. 22 shows a conceptual drawing of a system including a forcesensitive touch device.

Described embodiments may include touch I/O device 21001 that canreceive touch input and force input (such as possibly including touchlocations and force of touch at those locations) for interacting withcomputing system 21003 (such as shown in the FIG. 1) via wired orwireless communication channel 21002. Touch I/O device 21001 may be usedto provide user input to computing system 21003 in lieu of or incombination with other input devices such as a keyboard, mouse, orpossibly other devices. In alternative embodiments, touch I/O device21001 may be used in conjunction with other input devices, such as inaddition to or in lieu of a mouse, trackpad, or possibly anotherpointing device. One or more touch I/O devices 21001 may be used forproviding user input to computing system 21003. Touch I/O device 21001may be an integral part of computing system 21003 (e.g., touch screen ona laptop) or may be separate from computing system 21003.

Touch I/O device 21001 may include a touch sensitive and force sensitivepanel which is wholly or partially transparent, semitransparent,non-transparent, opaque or any combination thereof. Touch I/O device21001 may be embodied as a touch screen, touch pad, a touch screenfunctioning as a touch pad (e.g., a touch screen replacing the touchpadof a laptop), a touch screen or touchpad combined or incorporated withany other input device (e.g., a touch screen or touchpad disposed on akeyboard, disposed on a trackpad or other pointing device), anymulti-dimensional object having a touch sensitive surface for receivingtouch input, or another type of input device or input/output device.

In one example, touch I/O device 21001 embodied as a touch screen mayinclude a transparent and/or semitransparent touch sensitive and forcesensitive panel at least partially or wholly positioned over at least aportion of a display. (Although the touch sensitive and force sensitivepanel is described as at least partially or wholly positioned over atleast a portion of a display, in alternative embodiments, at least aportion of circuitry or other elements used in embodiments of the touchsensitive and force sensitive panel may be at least positioned partiallyor wholly positioned under at least a portion of a display, interleavedwith circuits used with at least a portion of a display, or otherwise.)According to this embodiment, touch I/O device 21001 functions todisplay graphical data transmitted from computing system 21003 (and/oranother source) and also functions to receive user input. In otherembodiments, touch I/O device 21001 may be embodied as an integratedtouch screen where touch sensitive and force sensitivecomponents/devices are integral with display components/devices. Instill other embodiments a touch screen may be used as a supplemental oradditional display screen for displaying supplemental or the samegraphical data as a primary display and to receive touch input,including possibly touch locations and force of touch at thoselocations.

Touch I/O device 21001 may be configured to detect the location of oneor more touches or near touches on device 21001, and where applicable,force of those touches, based on capacitive, resistive, optical,acoustic, inductive, mechanical, chemical, or electromagneticmeasurements, in lieu of or in combination or conjunction with anyphenomena that can be measured with respect to the occurrences of theone or more touches or near touches, and where applicable, force ofthose touches, in proximity to deice 21001. Software, hardware, firmwareor any combination thereof may be used to process the measurements ofthe detected touches, and where applicable, force of those touches, toidentify and track one or more gestures. A gesture may correspond tostationary or non-stationary, single or multiple, touches or neartouches, and where applicable, force of those touches, on touch I/Odevice 21001. A gesture may be performed by moving one or more fingersor other objects in a particular manner on touch I/O device 21001 suchas tapping, pressing, rocking, scrubbing, twisting, changingorientation, pressing with varying pressure and the like at essentiallythe same time, contiguously, consecutively, or otherwise. A gesture maybe characterized by, but is not limited to a pinching, sliding, swiping,rotating, flexing, dragging, tapping, pushing and/or releasing, or othermotion between or with any other finger or fingers, or any other portionof the body or other object. A single gesture may be performed with oneor more hands, or any other portion of the body or other object by oneor more users, or any combination thereof.

Computing system 21003 may drive a display with graphical data todisplay a graphical user interface (GUI). The GUI may be configured toreceive touch input, and where applicable, force of that touch input,via touch I/O device 21001. Embodied as a touch screen, touch I/O device21001 may display the GUI. Alternatively, the GUI may be displayed on adisplay separate from touch I/O device 21001. The GUI may includegraphical elements displayed at particular locations within theinterface. Graphical elements may include but are not limited to avariety of displayed virtual input devices including virtual scrollwheels, a virtual keyboard, virtual knobs or dials, virtual buttons,virtual levers, any virtual UI, and the like. A user may performgestures at one or more particular locations on touch I/O device 21001which may be associated with the graphical elements of the GUI. In otherembodiments, the user may perform gestures at one or more locations thatare independent of the locations of graphical elements of the GUI.Gestures performed on touch I/O device 21001 may directly or indirectlymanipulate, control, modify, move, actuate, initiate or generally affectgraphical elements such as cursors, icons, media files, lists, text, allor portions of images, or the like within the GUI. For instance, in thecase of a touch screen, a user may directly interact with a graphicalelement by performing a gesture over the graphical element on the touchscreen. Alternatively, a touch pad generally provides indirectinteraction. Gestures may also affect non-displayed GUI elements (e.g.,causing user interfaces to appear) or may affect other actions withincomputing system 21003 (e.g., affect a state or mode of a GUI,application, or operating system). Gestures may or may not be performedon touch I/O device 21001 in conjunction with a displayed cursor. Forinstance, in the case in which gestures are performed on a touchpad, acursor (or pointer) may be displayed on a display screen or touch screenand the cursor may be controlled via touch input, and where applicable,force of that touch input, on the touchpad to interact with graphicalobjects on the display screen. In other embodiments in which gesturesare performed directly on a touch screen, a user may interact directlywith objects on the touch screen, with or without a cursor or pointerbeing displayed on the touch screen.

Feedback may be provided to the user via communication channel 21002 inresponse to or based on the touch or near touches, and where applicable,force of those touches, on touch I/O device 21001. Feedback may betransmitted optically, mechanically, electrically, olfactory,acoustically, haptically, or the like or any combination thereof and ina variable or non-variable manner.

Attention is now directed towards embodiments of a system architecturethat may be embodied within any portable or non-portable deviceincluding but not limited to a communication device (e.g. mobile phone,smart phone), a multi-media device (e.g., MP3 player, TV, radio), aportable or handheld computer (e.g., tablet, netbook, laptop), a desktopcomputer, an All-In-One desktop, a peripheral device, or any other(portable or non-portable) system or device adaptable to the inclusionof system architecture 22000, including combinations of two or more ofthese types of devices. FIG. 2 is a block diagram of one embodiment ofsystem 22000 that generally includes one or more computer-readablemediums 22001, processing system 22004, Input/Output (I/O) subsystem22006, electromagnetic frequency (EMF) circuitry (such as possibly radiofrequency or other frequency circuitry) 22008 and audio circuitry 22010.These components may be coupled by one or more communication buses orsignal lines 22003. Each such bus or signal line may be denoted in theform 22003-X, where X can be a unique number. The bus or signal line maycarry data of the appropriate type between components; each bus orsignal line may differ from other buses/lines, but may perform generallysimilar operations.

It should be apparent that the architecture shown in FIG. 1-2 is onlyone example architecture of system 22000, and that system 22000 couldhave more or fewer components than shown, or a different configurationof components. The various components shown in FIG. 1-2 can beimplemented in hardware, software, firmware or any combination thereof,including one or more signal processing and/or application specificintegrated circuits.

EMF circuitry 22008 is used to send and receive information over awireless link or network to one or more other devices and includeswell-known circuitry for performing this function. EMF circuitry 22008and audio circuitry 22010 are coupled to processing system 22004 viaperipherals interface 22016. Interface 22016 includes various knowncomponents for establishing and maintaining communication betweenperipherals and processing system 22004. Audio circuitry 22010 iscoupled to audio speaker 22050 and microphone 22052 and includes knowncircuitry for processing voice signals received from interface 22016 toenable a user to communicate in real-time with other users. In someembodiments, audio circuitry 22010 includes a headphone jack (notshown).

Peripherals interface 22016 couples the input and output peripherals ofthe system to processor 22018 and computer-readable medium 22001. One ormore processors 22018 communicate with one or more computer-readablemediums 22001 via controller 22020. Computer-readable medium 22001 canbe any device or medium that can store code and/or data for use by oneor more processors 22018. Medium 22001 can include a memory hierarchy,including but not limited to cache, main memory and secondary memory.The memory hierarchy can be implemented using any combination of RAM(e.g., SRAM, DRAM, DDRAM), ROM, FLASH, magnetic and/or optical storagedevices, such as disk drives, magnetic tape, CDs (compact disks) andDVDs (digital video discs). Medium 22001 may also include a transmissionmedium for carrying information-bearing signals indicative of computerinstructions or data (with or without a carrier wave upon which thesignals are modulated). For example, the transmission medium may includea communications network, including but not limited to the Internet(also referred to as the World Wide Web), intranet(s), Local AreaNetworks (LANs), Wide Local Area Networks (WLANs), Storage Area Networks(SANs), Metropolitan Area Networks (MAN) and the like.

One or more processors 22018 run various software components stored inmedium 22001 to perform various functions for system 22000. In someembodiments, the software components include operating system 22022,communication module (or set of instructions) 22024, touch andforce-of-force processing module (or set of instructions) 22026,graphics module (or set of instructions) 22028, and one or moreapplications (or set of instructions) 22030. Each of these modules andabove noted applications correspond to a set of instructions forperforming one or more functions described above and the methodsdescribed in this application (e.g., the computer-implemented methodsand other information processing methods described herein). Thesemodules (i.e., sets of instructions) need not be implemented as separatesoftware programs, procedures or modules, and thus various subsets ofthese modules may be combined or otherwise rearranged in variousembodiments. In some embodiments, medium 22001 may store a subset of themodules and data structures identified above. Furthermore, medium 22001may store additional modules and data structures not described above.

Operating system 22022 includes various procedures, sets ofinstructions, software components and/or drivers for controlling andmanaging general system tasks (e.g., memory management, storage devicecontrol, power management, etc.) and facilitates communication betweenvarious hardware and software components.

Communication module 22024 facilitates communication with other devicesover one or more external ports 22036 or via EMF circuitry 22008 andincludes various software components for handling data received from EMFcircuitry 22008 and/or external port 22036.

Graphics module 22028 includes various known software components forrendering, animating and displaying graphical objects on a displaysurface. In embodiments in which touch I/O device is a touch sensitiveand force sensitive display (e.g., touch screen), graphics module 22028includes components for rendering, displaying, and animating objects onthe touch sensitive and force sensitive display.

One or more applications 22030 can include any applications installed onsystem 22000, including without limitation, a browser, address book,contact list, email, instant messaging, word processing, keyboardemulation, widgets, JAVA-enabled applications, encryption, digitalrights management, voice recognition, voice replication, locationdetermination capability (such as that provided by the globalpositioning system, also sometimes referred to herein as “GPS”), a musicplayer, and otherwise.

Touch and force-of-force processing module 22026 includes varioussoftware components for performing various tasks associated with touchI/O device including but not limited to receiving and processing touchinput and force-of-touch input received from I/O device 22012 via touchI/O device controller 22032.

I/O subsystem 22006 is coupled to touch I/O device. The I/O subsystemmay be additionally coupled to one or more other I/O devices forcontrolling or performing various functions. Touch I/O devicecommunicates with processing system 22004 via touch I/O devicecontroller 22032, which includes various components for processing usertouch input and force-of-touch input (e.g., scanning hardware). One ormore other input controllers receives/sends electrical signals from/toother I/O devices. Other I/O devices may include physical buttons,dials, slider switches, sticks, keyboards, touch pads, additionaldisplay screens, or any combination thereof.

If embodied as a touch screen, touch I/O device displays visual outputto the user in a GUI. The visual output may include text, graphics,video, and any combination thereof. Some or all of the visual output maycorrespond to user-interface objects. Touch I/O device forms atouch-sensitive and force-sensitive surface that accepts touch input andforce-of-touch input from the user. Touch I/O device and touch screencontroller 22032 (along with any associated modules and/or sets ofinstructions in medium 22001) detects and tracks touches or neartouches, and where applicable, force of those touches (and any movementor release of the touch, and any change in the force of the touch) ontouch I/O device and converts the detected touch input andforce-of-touch input into interaction with graphical objects, such asone or more user-interface objects. In the case in which device 22012 isembodied as a touch screen, the user can directly interact withgraphical objects that are displayed on the touch screen. Alternatively,in the case in which device 22012 is embodied as a touch device otherthan a touch screen (e.g., a touch pad or trackpad), the user mayindirectly interact with graphical objects that are displayed on aseparate display screen embodied as a separate I/O device.

Touch I/O device may be analogous to the multi-touch sensitive surfacedescribed in the following U.S. Pat. No. 6,323,846 (Westerman et al.),U.S. Pat. No. 6,570,557 (Westerman et al.), and/or U.S. Pat. No.6,677,932 (Westerman), and/or U.S. Patent Publication 2002/0015024A1,each of which is hereby incorporated by reference.

Embodiments in which touch I/O device is a touch screen, the touchscreen may use LCD (liquid crystal display) technology, LPD (lightemitting polymer display) technology, OLED (organic LED), or OEL(organic electro luminescence), although other display technologies maybe used in other embodiments.

Feedback may be provided by touch I/O device based on the user's touch,and force-of-touch, input as well as a state or states of what is beingdisplayed and/or of the computing system. Feedback may be transmittedoptically (e.g., light signal or displayed image), mechanically (e.g.,haptic feedback, touch feedback, force feedback, or the like),electrically (e.g., electrical stimulation), olfactory, acoustically(e.g., beep or the like), or the like or any combination thereof and ina variable or non-variable manner.

System 22000 also includes power system 22044 for powering the varioushardware components and may include a power management system, one ormore power sources, a recharging system, a power failure detectioncircuit, a power converter or inverter, a power status indicator and anyother components typically associated with the generation, managementand distribution of power in portable devices.

In some embodiments, peripherals interface 22016, one or more processors22018, and memory controller 22020 may be implemented on a single chip,such as processing system 22004. In some other embodiments, they may beimplemented on separate chips.

In one embodiment, an example system includes a force sensor 22014coupled to the electronic device 21000, such as coupled to a forcesensor controller 22034. For example, the force sensor controller 22034can be included in the I/O subsystem 22006. The force sensor controller22034 can be coupled to a processor or other computing device, such asthe processor 22018 or the secure processor 22040, with the effect thatinformation from the force sensor controller 22034 can be measured,calculated, computed, or otherwise manipulated. In one embodiment, theforce sensor 22014 can make use of one or more processors or othercomputing devices, coupled to or accessible to the electronic device21000, such as the processor 22018, the secure processor 22040, orotherwise. In alternative embodiments, the force sensor controller 22034can make use of one or more analog circuits or other specializedcircuits, coupled to or accessible to the electronic device 21000, suchas might be coupled to the I/O subsystem 22006.

In one embodiment, as described above, the force sensor 22014 determinesa measure of applied force from a user contacting the electronic device21000. When the user applied force to the force sensor 22014, the coverglass displaces, bends, twists or otherwise moves in response to theapplied force, pressing an upper support towards a lower support, andcompressing a bending beam located between the two. This has the effectthat a strain probe can determine an amount of stain applied to thebending beam, thus the amount of applied force which caused thatmovement. Although reference is made herein to “cover glass,” it shouldbe appreciated that the covering element may be any suitableoptically-transparent (or near-transparent) material. In someembodiments, sapphire and/or polycarbonate may be used as a coveringelement. Accordingly, references to a “cover glass” herein are meant toencompass other covering elements, including both sapphire andpolycarbonate.

Certain aspects of the embodiments described in the present disclosuremay be provided as a computer program product, or software, that mayinclude, for example, a computer-readable storage medium or anon-transitory machine-readable medium having stored thereoninstructions, which may be used to program a computer system (or otherelectronic devices) to perform a process according to the presentdisclosure. A non-transitory machine-readable medium includes anymechanism for storing information in a form (e.g., software, processingapplication) readable by a machine (e.g., a computer). Thenon-transitory machine-readable medium may take the form of, but is notlimited to, a magnetic storage medium (e.g., floppy diskette, videocassette, and so on); optical storage medium (e.g., CD-ROM);magneto-optical storage medium; read only memory (ROM); random accessmemory (RAM); erasable programmable memory (e.g., EPROM and EEPROM);flash memory; and so on.

While the present disclosure has been described with reference tovarious embodiments, it will be understood that these embodiments areillustrative and that the scope of the disclosure is not limited tothem. Many variations, modifications, additions, and improvements arepossible. More generally, embodiments in accordance with the presentdisclosure have been described in the context of particular embodiments.Functionality may be separated or combined in procedures differently invarious embodiments of the disclosure or described with differentterminology. These and other variations, modifications, additions, andimprovements may fall within the scope of the disclosure as defined inthe claims that follow.

Alternative Embodiments

After reading this application, those skilled in the art would recognizethat techniques for obtaining information with respect to applied forceand contact on a touch I/O device, and using that associated informationto determine amounts and locations of applied force and contact on atouch I/O device, is responsive to, and transformative of, real-worlddata such as relative capacitance and compressibility received fromapplied force or contact by a user's finger, and provides a useful andtangible result in the service of detecting and using applied force andcontact with a touch I/O device. Moreover, after reading thisapplication, those skilled in the art would recognize that processing ofapplied force and contact sensor information by a computing deviceincludes substantial computer control and programming, involvessubstantial records of applied force and contact sensor information, andinvolves interaction with applied force and contact sensor hardware andoptionally a user interface for use of applied force and contact sensorinformation.

While the present disclosure has been described with reference tovarious embodiments, it will be understood that these embodiments areillustrative and that the scope of the disclosure is not limited tothem. Many variations, modifications, additions, and improvements arepossible. More generally, embodiments in accordance with the presentdisclosure have been described in the context of particular embodiments.Functionality may be separated or combined in procedures differently invarious embodiments of the disclosure or described with differentterminology. These and other variations, modifications, additions, andimprovements may fall within the scope of the disclosure as defined inthe claims that follow.

Although embodiments have been fully described with reference to theaccompanying drawings, it is to be noted that various changes andmodifications will become apparent to those skilled in the art. Suchchanges and modifications are to be understood as being included withinthe scope of the various embodiments as defined by the appended claims.The foregoing description has broad application. Accordingly, thediscussion of any embodiment is meant only to be an example and is notintended to suggest that the scope of the disclosure, including theclaims, is limited to these examples.

What is claimed is:
 1. An electronic device, comprising: a frame atleast partially enclosing an interior of the electronic device, theframe having an open end; a cover glass covering the open end of theframe; a plurality of strain probes positioned under the cover glass,between the cover glass and the frame, and arranged to output aplurality of strain signals responsive to one or more forces applied tothe electronic device; and a force processing module configured to atleast calculate an amount of force applied to the electronic devicebased on the plurality of stain signals.
 2. The electronic device ofclaim 1, wherein: the plurality of strain probes is positioned along aset of beams; the set of beams is positioned along opposite edges of theframe; each beam in the set of beams is rigidly connected to arespective one of the opposite edges of the frame, at each end of thebeam.
 3. The electronic device of claim 1, wherein the plurality ofstrain probes is positioned along opposite edges of the frame.
 4. Theelectronic device of claim 1, wherein: the plurality of strain probes ispositioned along a set of beams; and the set of beams is positionedalong opposite edges of the frame.
 5. The electronic device of claim 4,wherein the set of beams is connected to the opposite edges of theframe.
 6. The electronic device of claim 4, wherein each beam in the setof beams is connected to an edge of the frame at each end of the beam.7. The electronic device of claim 4, wherein each beam in the set ofbeams is rigidly connected to a respective one of the opposite edges ofthe frame.
 8. The electronic device of claim 4, wherein the set of beamscomprises a set of bending beams.
 9. The electronic device of claim 4,further comprising: a plurality of clips, wherein each clip attaches abeam end to an edge of the frame, each clip having one of the pluralityof strain probes disposed thereon.
 10. The electronic device of claim 1,further comprising: an opaque border region located along a perimeter ofthe cover glass; wherein, the plurality of strain probes is positionedunder the opaque border region.
 11. An electronic device, comprising: aframe at least partially enclosing an interior of the electronic device;a cover glass connected to the frame; a set of strain probes positionedunder the cover glass along a perimeter of the cover glass; wherein: theset of strain probes comprise a first strain probe and a second strainprobe connected by a first beam, and a third strain probe and a fourthstrain probe connected by a second beam.
 12. The electronic device ofclaim 11, further comprising: a force processing module configured tocalculate an amount of force applied to the electronic device based on aset of strain signals produced by the set of strain probes; wherein: thefirst beam is positioned along a first edge of the frame and connectedto the first edge at each end of the first beam; and the second beam ispositioned along a second edge of the frame, opposite the first edge,and connected to the second edge at each end of the second beam.
 13. Theelectronic device of claim 11, further comprising: a force processingmodule configured to calculate an amount of force applied to theelectronic device based on a set of strain signals produced by the setof strain probes.
 14. The electronic device of claim 11, wherein the setof strain probes is positioned along opposite edges of the frame. 15.The electronic device of claim 11, wherein: the first beam is positionedalong a first edge of the frame; and the second beam is positioned alonga second edge of the frame, the second edge opposite the first edge. 16.The electronic device of claim 15, wherein: the first beam is connectedto the first edge; and the second beam is connected to the second edge.17. The electronic device of claim 15, wherein: the first beam isconnected to the first edge at each end of the first beam; and thesecond beam is connected to the second edge at each end of the secondbeam.
 18. The electronic device of claim 15, wherein: the first beam isrigidly connected to the first edge; and the second beam is rigidlyconnected to the second edge.
 19. The electronic device of claim 11,wherein the first beam and the second beam are bending beams.
 20. Theelectronic device of claim 11, wherein the cover glass is movablyconnected to the frame.